Data communications including audio communications often have different security levels depending on the content of the communication. Different security levels, particularly in military applications, are designated by a standardized color coding scheme. For example, black represents a relatively low security level, which applies to unclassified communications. Red represents a relatively high security level, which applies to secret (i.e., classified) communications. Pink represents an intermediate security level between unclassified communications and secret communications, which applies to commercial secure communications. Additional security levels can also be provided as needed.
To effectively distribute data communications having different security levels, communication systems are employed which segregate the data communications at different security levels from one another and maintain proper compartmentalization of the communications as they are transferred within the system. Conventional communication systems commonly provide separate communication media for each security level enabled. Thus, for example, if the communication system enables the distribution of data communications at black and red security levels, the system provides two separate communication media, one for the black security level and one for the red security level.
Each set of communication media has its own dedicated wiring and input/output ports which substantially and undesirably increase the weight, complexity, power requirements, and cost of the communication system. Conventional communication systems may also rely on trusted software for the specific functions of segregating the data communications and maintaining compartmentalization as the data communications are transferred within the communication system. Therefore, whenever the trusted software is modified, the security of the communication system must be reevaluated, which is both time-consuming and costly.
The present invention recognizes a need for a secure communication system which overcomes the above-recited drawbacks of conventional systems. Accordingly, it is generally an object of the present invention to provide a communication system which effectively maintains each data communication routed within the system at one of a plurality of preassigned security levels. More particularly, it is an object of the present invention to provide a communication system which segregates and maintains data communications at separate security levels internal to the system by a relatively simple yet effective non-classified mechanism. It is still more particularly an object of the present invention to provide a communication system which transfers data communications, regardless of their preassigned security level, within the system on common communication media. It is another object of the present invention to provide a communication system which is not primarily software based with respect to system security and, more specifically, which is hardware based with respect to the security functions of segregating data communications and maintaining compartmentalization of the data communications as they are transferred within the system. It is a further object of the present invention to provide a communication system wherein the remaining nonsystem-related functionality is primarily software based. It is still a further object of the present invention to provide a communication system, wherein the software of the system can be freely modified without necessitating reevaluation of system security.
These objects and others are accomplished in accordance with the invention described hereafter.